99’ LEGO, 30th. 2.2. Auto. 150k. Stock. New factory front o2 (replaced because I had it laying around not because of issue) new knock sensor. New coil, NGK plugs and wires. New fuel filter.

OUT OF NOWHERE—Intermittent- Car bogs, dangerously so, anywhere outside the first and last 1/8 of throttle range. If I have the car mid throttle- BOG. As I let back out and get in that first 1/8 again it will downshift and surge with life.

Rusty filler neck that throws EVaP code and leaks when filling, sometimes.

Never runs bad when CEL illuminated. Never throws CEL when it runs rough.

This is the 3rd Subaru I’ve had with this issue. Solved those with o2 sensors. The other two didn’t have holes in either of the filler necks, but each had EVAP ghosts. 

Have you looked into your TPS (throttle position sensor)? 

You can remove it, pop the cover off (drill the plastic tabs on the mounting plate) and clean the contact slides and tab arms. These can sometimes gunk up and cause TPS reading issues for the ECU. 

Have you checked codes? I’d be starting there. 

Cheers 

Bennie

The airbox isn't sealed properly. There's service bulletins on this issue. 

GD

21 hours ago, GeneralDisorder said:

The airbox isn't sealed properly. There's service bulletins on this issue. 

GD

 

Yeah, I'll bet.

99 2.2 is in a Legacy is the weird year with 2 air filter boxes.  If the second one (long skinny) a teh throttle body is not sealed well, it's an unmetered air leak.

Check that he tabs are engaged with teh bottom lips of the air box in the back fitler box.